“My guess is that once the guidelines are released their content will lead everyone to wonder why it took so long for them to be released and that they will represent the start of a process, rather than its conclusion.”

As to the last part, check out section V of the memo:

“the Director of the Office of Management and Budget (OMB) will be issuing guidance to OMB staff concerning the review of draft executive branch testimony on scientific issues prepared for presentation to the Congress. This guidance will provide standards that are to be applied during the review of scientific testimony.”

A necessary step, certainly. And each agency has been given 120 days to develop and implement policies connected to the recommendations, so there will be more to this than what happened today.